MG Car Repair: signal lights just stopped working, hazard warning switch, signal switch

Question
QUESTION: I have changed out my signal switch already.  ( I don't think it was very good cause it was slow) My battery then went dead, changed it myself, still have no signal lights. I have bought a new signal switch.  Have checked fuses and bulbs.  Could this be my problem (signal switch) or do you have another suggestion. As I said the signals were working, then suddenly quit while driving. My car is a 79 MGB. Thanks

ANSWER: Hi Margaret.
If the turn indicators have suddenly stopped working on both sides of the car, then I would guess that there is a fault in the hazard warning switch.  

Try operating the hazard warning switch.  Do all 4 turn indicators work OK?  If so, try turning the hazard switch on and off a few times and you will probably find that the signal switch starts to work again.

If this doesn't cure the fault, get back to me.

---------- FOLLOW-UP ----------

QUESTION: Mr. Jones,
I tried the hazard warning switch as you suggested without any luck so I went ahead and changed out my signal switch under the dash.  Success!  But... they are blinking very slowly.  Any suggestions.
Thanks,
Margaret

Answer
The speed of the turn indicators is governed by the two-wire relay unit clipped to the bulkhead.  This is an old mechanical design.  You could try fitting a new turn indicator relay.  Personally, I would fit a modern 3-wire relay.  These have a transistorised speed governor unit inside.  The third wire goes to earth (ground) using the screw that holds the clip.